Understanding The Mldv2 Snooping Querier - Cisco 7604 Configuration Manual
Ios software configuration guide
Hide thumbs
Also See for 7604:
- Configuration manual (742 pages) ,
- Installation manual (324 pages) ,
- User manual (98 pages)
Table of Contents
Advertisement
Chapter 29
Configuring MLDv2 Snooping for IPv6 Multicast Traffic
If the filter mode change record was from the only remaining interface with hosts interested in the group,
and MLDv2 snooping does not receive an MLDv2 report in response to the general query, MLDv2
snooping removes the group entry and relays the MLDv2 filter mode change record to the multicast
router. If the multicast router receives no reports from a VLAN, the multicast router removes the group
for the VLAN from its MLDv2 cache.
The interval for which the router waits before updating the table entry is called the "last member query
interval." To configure the interval, enter the ipv6 mld snooping last-member-query-interval interval
command.
Fast-Leave Processing
Fast-leave processing is enabled by default. To disable fast-leave processing, turn off explicit-host
tracking.
Fast-leave processing is implemented by maintaining source-group based membership information in
software while also allocating LTL indexes on a MAC GDA basis.
When fast-leave processing is enabled, hosts send BLOCK_OLD_SOURCES{src-list} messages for a
specific group when they no longer want to receive traffic from that source. When the router receives
such a message from a host, it parses the list of sources for that host for the given group. If this source list
is exactly the same as the source list received in the leave message, the router removes the host from the LTL
index and stops forwarding this multicast group traffic to this host.
If the source lists do not match, the router does not remove the host from the LTL index until the host is
no longer interested in receiving traffic from any source.
Disabling explicit host tracking disables fast-leave processing and proxy reporting.
Note
Understanding the MLDv2 Snooping Querier
Use the MLDv2 snooping querier to support MLDv2 snooping in a VLAN where PIM and MLDv2 are
not configured because the multicast traffic does not need to be routed.
In a network where IP multicast routing is configured, the IP multicast router acts as the MLDv2 querier.
If the IP-multicast traffic in a VLAN only needs to be Layer 2 switched, an IP-multicast router is not
required, but without an IP-multicast router on the VLAN, you must configure another router as the
MLDv2 querier so that it can send queries.
When enabled, the MLDv2 snooping querier sends out periodic MLDv2 queries that trigger MLDv2
report messages from the router that wants to receive IP multicast traffic. MLDv2 snooping listens to
these MLDv2 reports to establish appropriate forwarding.
You can enable the MLDv2 snooping querier on all the Cisco 7600 series routers in the VLAN, but for
each VLAN that is connected to switches that use MLDv2 to report interest in IP multicast traffic, you
must configure at least one router as the MLDv2 snooping querier.
You can configure a router to generate MLDv2 queries on a VLAN regardless of whether or not IP
multicast routing is enabled.
OL-4266-08
Cisco 7600 Series Router Cisco IOS Software Configuration Guide, Release 12.2SX
Understanding How MLDv2 Snooping Works
29-7
- Quick Links:
- Supported Hardware and Software
Hide quick links:
Advertisement
Chapters
Table of Contents
